commit 0b80a0e500d5132ca4dd77403b5a4c7f23f26a80 Author: Taylor Yu catalyst@torproject.org Date: Tue May 1 18:13:37 2018 -0500
Factor out warn_early_consensus()
Factor out the early consensus warning code from networkstatus_set_current_consensus() into a new function warn_early_consensus(). --- src/or/networkstatus.c | 62 ++++++++++++++++++++++++++++++++++---------------- src/or/networkstatus.h | 2 ++ 2 files changed, 45 insertions(+), 19 deletions(-)
diff --git a/src/or/networkstatus.c b/src/or/networkstatus.c index 44c0638c2..ace9fc94a 100644 --- a/src/or/networkstatus.c +++ b/src/or/networkstatus.c @@ -1751,6 +1751,48 @@ handle_missing_protocol_warning(const networkstatus_t *c, handle_missing_protocol_warning_impl(c, 1); }
+/** + * Check whether we received a consensus that appears to be coming + * from the future. Because we implicitly trust the directory + * authorities' idea of the current time, we produce a warning if we + * get an early consensus. + * + * If we got a consensus that is time stamped far in the past, that + * could simply have come from a stale cache. Possible ways to get a + * consensus from the future can include: + * + * - enough directory authorities have wrong clocks + * - directory authorities collude to produce misleading time stamps + * - our own clock is wrong (this is by far the most likely) + * + * We neglect highly improbable scenarios that involve actual time + * travel. + */ +STATIC void +warn_early_consensus(const networkstatus_t *c, const char *flavor, + time_t now) +{ +/** If a consensus appears more than this many seconds before its declared + * valid-after time, declare that our clock is skewed. */ +#define EARLY_CONSENSUS_NOTICE_SKEW 60 + + if (now < c->valid_after - EARLY_CONSENSUS_NOTICE_SKEW) { + char tbuf[ISO_TIME_LEN+1]; + char dbuf[64]; + long delta = now - c->valid_after; + char *flavormsg = NULL; + format_iso_time(tbuf, c->valid_after); + format_time_interval(dbuf, sizeof(dbuf), delta); + log_warn(LD_GENERAL, "Our clock is %s behind the time published in the " + "consensus network status document (%s UTC). Tor needs an " + "accurate clock to work correctly. Please check your time and " + "date settings!", dbuf, tbuf); + tor_asprintf(&flavormsg, "%s flavor consensus", flavor); + clock_skew_warning(NULL, delta, 1, LD_GENERAL, flavormsg, "CONSENSUS"); + tor_free(flavormsg); + } +} + /** Try to replace the current cached v3 networkstatus with the one in * <b>consensus</b>. If we don't have enough certificates to validate it, * store it in consensus_waiting_for_certs and launch a certificate fetch. @@ -2053,25 +2095,7 @@ networkstatus_set_current_consensus(const char *consensus, write_str_to_file(consensus_fname, consensus, 0); }
-/** If a consensus appears more than this many seconds before its declared - * valid-after time, declare that our clock is skewed. */ -#define EARLY_CONSENSUS_NOTICE_SKEW 60 - - if (now < c->valid_after - EARLY_CONSENSUS_NOTICE_SKEW) { - char tbuf[ISO_TIME_LEN+1]; - char dbuf[64]; - long delta = now - c->valid_after; - char *flavormsg = NULL; - format_iso_time(tbuf, c->valid_after); - format_time_interval(dbuf, sizeof(dbuf), delta); - log_warn(LD_GENERAL, "Our clock is %s behind the time published in the " - "consensus network status document (%s UTC). Tor needs an " - "accurate clock to work correctly. Please check your time and " - "date settings!", dbuf, tbuf); - tor_asprintf(&flavormsg, "%s flavor consensus", flavor); - clock_skew_warning(NULL, delta, 1, LD_GENERAL, flavormsg, "CONSENSUS"); - tor_free(flavormsg); - } + warn_early_consensus(c, flavor, now);
/* We got a new consesus. Reset our md fetch fail cache */ microdesc_reset_outdated_dirservers_list(); diff --git a/src/or/networkstatus.h b/src/or/networkstatus.h index 0c325959d..b133f43dc 100644 --- a/src/or/networkstatus.h +++ b/src/or/networkstatus.h @@ -153,6 +153,8 @@ int any_client_port_set(const or_options_t *options); #ifdef TOR_UNIT_TESTS STATIC int networkstatus_set_current_consensus_from_ns(networkstatus_t *c, const char *flavor); +STATIC void warn_early_consensus(const networkstatus_t *c, const char *flavor, + time_t now); extern networkstatus_t *current_ns_consensus; extern networkstatus_t *current_md_consensus; #endif /* defined(TOR_UNIT_TESTS) */